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Cool It! is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store.

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The last solar eclipse of this millennium occurred on August 11, 1999. Amateurs and professionals alike used this opportunity to witness one of the most brilliant natural phenomenon. This was a total...more

An eclipse of the Sun occurs when the Earth passes through the Moon's shadow. A total eclipse of the Sun takes place only during a new moon, when the Moon is directly between the Sun and the Earth and...more

Eclipses have been monitored for centuries, but it was only recently that we understood what really occurs. Eclipses have always been fascinating to watch, but they weren't always welcome. For many years,...more

Rising above the Sun's chromosphere , the temperature jumps sharply from a few tens of thousands of kelvins to as much as a few million kelvins in the Sun's outer atmosphere, the solar corona. Understanding...more

Most of the energy we receive from the Sun is the visible (white) light emitted from the photosphere. The photosphere is one of the coolest regions of the Sun (6000 K), so only a small fraction (0.1%)...more

The gas in the solar corona is at very high temperatures (typically 1-2 million kelvins in most regions) so it is almost completely in a plasma state (made up of charged particles, mostly protons and electrons)....more

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are "dark" because they are cooler than their surroundings. A large sunspot might have a central temperature of...more